A supply line structure is described in non-prepublished German Patent Application No. 101 42 410 filed by the applicants.
A supply line structure of this type is intended to support communication between various electrical components, for example between a door control unit and a seat control unit, and also to supply energy to these components. This approach is referred to as power line communications. Here it has been found to be useful to restructure the wiring harness that is already present in the existing technology in such a way that the supply lines are arranged in a star structure having at least one star point. In the known supply line structure, the use of so-called twisted pair cables to supply power to the components has proven to be advantageous. These cables are understood to mean double cores or conductor litz wires that are twisted together and that result in an improvement in interference immunity and that have various characteristic impedances that are a function of the degree of twisting that is carried out. Since a star point within a conductor system may always be regarded as a parallel connection of resistors, a very low impedance results for the star point, which, at the star point, leads to undesirable reflections of the wave propagating in a supply line branch in the direction of the star point. However, this effect may be suppressed by wiring of the line branch in the area of the star point, as proposed in the aforesaid German Patent Application No. 101 42 410.
A further problem with the supply line structure described above is, however, the transmission of high electrical currents. If the aforesaid twisted pair cables are used, their limited cross-sectional area, which makes them more practical to twist, imposes limits as to the current that may be carried. Moreover, it is expensive to manufacture twisted pair cables that have a large cross-sectional area.